Michele D'Ambrosio

Parthenolide and its photochemically synthesized 1(10)Z isomer: chemical reactivity and structure–activity relationship studies in human leucocyte chemotaxis

The present study has achieved the photochemical conversion of a germacrolide into a melampolide. The investigation on their chemical properties allowed us to evaluate the minimum interatomic distance needed for transannular bridging of C(10) ring in germacrolides and to explain the regiochemical selectivity of electrophilic cyclizations. The antiinflammatory activity of parthenolide and its semisynthetic derivatives was evaluated by in vitro chemotaxis assay with human neutrophiles. These structure-activity relationship studies have led to hypothesize a new pharmacophore and have provided useful information for computationally designed drugs.

Degraded limonoids from Melia azedarach and biogenetic implications

The roots of Melia azedarach yielded three new degraded limonoids: teracrylmelazolide A, melazolide A and teracrylmelazolide B, possessing a previously undescribed skeleton. The known pyroangolensolide, fraxinellone and its three derivatives, 30-hydroxyfraxinellone, 9 alpha- and 9 beta-hydroxyfraxinellone, were also isolated. Their stereochemisty was elucidated on the basis of spectral data and chemical reactions.

Epinardins A-D, new pyrroloiminoquinone alkaloids of undetermined deep-water green demosponges from pre-Antarctic Indian ocean

Abstract Four novel pyrroloiminoquinone alkaloids that differ from members of the discorhabdin/prianosin family for having an allylic alcohol functionality in place of the enone system, epinardins A-D (8–11), have been isolated from undetermined deep-water green demosponges collected in pre-Antarctic waters near the Crozet Islands. Relative stereochemistry has been fully assigned from high-field NMR spectra. Epinardin C (10) proved strongly cytotoxic towards doxorubicin-resistant L1210/DX tumoural cells in vitro.

Agelastatin a, a new skeleton cytotoxic alkaloid of the oroidin family. Isolation from the axinellid sponge Agelas dendromorpha of the coral sea

Agelastatin A, isolated from the axinellid sponge Agelas dendromorpha of the Coral Sea, is a new-skeleton alkaloid with, unusually for the oroidin family to which it belongs, marked cytotoxicity toward tumour cells in culture.

Cavernicolin-1 and cavernicolin-2, epimeric dibromolactams from the mediterranean sponge aplysina (venongia) cavernicola

Abstract Cavernicolin-1 and Cavernicolin-2, two epimeric compounds having a γ-lactam ring fused to a dibromocyclohexenone ring, have been isolated from the Mediterranean sponge Aplysina (Verongia) cavernicola .

On the first marine natural product having low enantiomeric purity

Resulting from enzymatic reactions, natural products are the standard of reference for high optical purity. In fact, natural products commonly reveal specific rotations from polarimetric measurements. The few cases of racemic natural products and, particularly, the rare cases of quasi-racemic natural products [1] are of special biological interest. Therefore, we are pleased to be able to report on the first case of a marine natural product (monobromocavernicolin, 1) with low enantiomeric purity. These results were obtained after a number of unsuccessful attempts to clarify the origin of small optical rotations with 3 and its C-2-epimer [2], all these products coming from the sponge Aplysina cavernicola.

Aztèquynol A, the first clearly defined, C-branched polyacetylene and the analogue Aztèquynol B. Isolation from the tropical marine sponge Petrosia sp.

Abstract Aztequynol A ( 1 ), isolated from the nepheliospongid sponge, Petrosia sp., from the Banc Azteque off New Caledonia, represents the first case of a structurally defined C-branched polyacetylene based on high-energy collisionally-activated decomposition tandem mass spectrometry of lithium adducts which may have wide application in natural product structural analysis.

Relative Contributions to Antitumoral Activity of Lipophilic vs. Polar Reactive Moieties in Marine Terpenoids

Marked cytotoxicity of norsesterterpenoids 3 and 4 vs. inactivity or low activity of the respective norditerpenoid analogues 2 and 1 towards KB tumoral cell lines suggest that the length of the lipophilic chain is an important factor while, per se the reactive peroxide functionality is not. Moreover, lower bioactivity towards the same cells of 1 than 2, and comparable activities of 3–5, show the unimportance per se of the highly electrophilic enone moiety. A strict need of molecular tailoring, so that weapons may reach the target in adaptive phenomena, may be at the basis of natural selection of these compounds and suggests strategies for the design of safer agents against cancer.

Glycerol enol ethers of the brachiopod Gryphus vitreus from the Tuscan archipelago

Long-chain free glycerol enol ethers, as well as monounsaturated and saturated β-methoxy-substituted glycerol ethers, have been isolated fromGryphus vitreus (Born, 1778) (Brachiopoda Articulata, Terebratulidae) collected in Tuscan archipelago waters, Thyrrenian Sea. This is the first description of secondary metabolites from brachiopods.

Chlorophyll-photosensitised photodegradation of caulerpenyne; a potentially harmful sesquiterpenoid from tropical green seaweeds in the genus Caulerpa

On exposure to daylight, caulerpenyne 1 in solution in the presence of oxygen and chlorophylls or pheophytins undergoes rapid, multifarious degradation involving a peculiar route through ynone 2, thus providing a model for detoxification from these and similar food web and seagrass potentially harmful terpenoids of caulerpalean green seaweeds in Mediterranean areas invaded by the tropical Caulerpa taxifolia.